The present embodiments relate generally to systems and methods for valve insertion and linestopping.
There are various instances in which it may become necessary or desirable to affect flow within an existing pipe, such as one that is subterraneously placed. Such pipes may carry gases, oil, water, or other fluids, and it may be desirable to temporarily or permanently stop the flow within the pipe.
Various valve insertion methods are known for inserting a valve in a line of an existing pipe. In general, a sealing housing having first and second portions may be coupled around an exterior surface of the existing pipe. A slit may be made in the existing pipe using a cutting machine without stopping passage of fluid. A gate, or sluice valve, is inserted into the slit portion of the existing pipe. The gate may be advanced to a position in which is inhibits flow through the existing pipe.
U.S. Pat. No. 6,622,747 B2 to Satos et al. and US Patent Application No. 2012/0222753 A1 to Satos et al. disclose devices for milling valve fittings in transmission pipes. However, in both the Satos patent and application, the mill is adapted to rotate about the transmission pipe. Such rotation about the transmission pipe makes it difficult to maintain an airtight seal about the transmission pipes, allowing leaks.
In various systems, a relatively large excavation is required in order to access the existing pipe and perform various operations. Moreover, the cutting machine generally either cuts an entire section of the pipe, or a section that is about 180 degrees along the upper surface of the pipe, prior to insertion of the gate. However, such large cuts to the pipe may adversely affect the integrity of the pipe.
Additionally, it may be difficult to attach a valve bonnet and a gate to the existing pipe after a cut is formed into the existing pipe. Still further, it also may be difficult or impossible to remove the valve bonnet and gate after a desired operation is performed. In some situations, a relatively expensive valve bonnet and gate therefore remain coupled to the existing pipe even in situations where it was only necessary to perform a relatively brief, single linestop.
Accordingly, it is an object of the present invention to provide a valve fitting milling system and method for use with transmission pipes, including but not limited to water, gas, sewage pipes and the like.
These and other objects will be readily evident upon a study of the specification and the accompanying drawings.